Vibrato signal generating apparatus for an electronic musical instrument

ABSTRACT

A vibrato signal generating apparatus for an electronic musical instrument characterized in that an AND gate circuit is interposed in a circuit connected between a high frequency oscillator and an octave frequency divider, and an astable multivibrator modulated by a vibrato oscillator is provided and is so arranged that the AND gate circuit is controlled by the output signal of the astable multivibrator.

UnitedStates Patent [191 Obayashi 11] 3,824,326 July 16, 1974 1 VIBRATO SIGNAL GENERATING APPARATUS FOR AN ELECTRONIC MUSICAL INSTRUMENT [75] Inventor: Nobuharu Obayashi, Shizuoka-ken,

Japan [73] Assignee: KabushikiKaisha KawaiGakki Seisakusho, Shizuoka-ken, Japan [22] Filed: June 6, 1973 [21] Appl. No.: 367,399

[30] Foreign Application Priority Data June 9, 1972 Japan 47-56841 [52] US. Cl. 84/125, 84/1.0l [51] Int. Cl. Gl0h 1/04 [58] Field of Search 84/1.0l, 1.24, 1.25, 1.03;

[56] References Cited UNITED STATES PATENTS 3,234,485 2/1966 Graser 84/125 X 3,259,852 7/1966 Todd 331/52 3,288,909 11/1966 Volodin 84/].25 X 3,479,440 11/1969 Martin et a1. 84/125 3,590,131 6/1971 3,601,518 8/1971 3,617,901 11/1971 Franssen 84/].01

Primary ExaminerRichard B. Wilkinson Assistant Examiner-U. Weldon Attorney, Agent, or Firm-Waters, Roditi, Schwartz & Nissen 1 [57] ABSTRACT A vibrato signal generating apparatus for an electronic musical instrument characterized in that an AND gate circuit is interposed in a circuit connected between a high frequency oscillator and an octave frequency divider, and an astable multivibrator modulated by a vibrato oscillator is provided and is so arranged that the AND gate circuit is controlled by the output signal of the astable multivibrator.

9 Claims, 6 Drawing Figures F T I 1 9 0r 1 [r I F/?Q I r 0m l Z 1 l l 1 m 1 1 L 3 PATENTEBJIMBIBH sum 1 or 3 F a [0581' 6 i 3 I E-l 2-00024 MHz (B) (7906-09Hz) (A**) (7463-68Hz (A) (7043-1OHz) (F) ('5917-87Hz) (F) (5587-26Hz) (E) 5277. 58H (13*) (4975-72Hz) (D) (469540Hz) V (6*) (4435-12 Hz (b 3 2- 2 Hz (B) (7902. 13 Hz) (A (7468- 2 Hz) (A) (704000 Hz) 6 664488 Hz) (6 (6271-93142 (F) (5919-91 Hz) (F) (5587-65 Hz) )(5274-O4Hz) (0") (4978- 03 Hz) (469864 Hz) 4484 92 Hz) PATENTEU L 1 74 samanr PAIENTED JUL 1 81974 SHEET 3 [IF 3 VIBRATO SIGNAL GENERATING APPARATUS FOR AN ELECTRONIC MUSICAL INSTRUMENT FIELD OF THE INVENTION This invention relates to an apparatus for generating a vibrato signal for an electronic musical instrument.

BACKGROUND A main oscillator for an electronic musical instrument must be very accurate. Accordingly, a quartz oscillator is generally used for the same.

It is, however, impossible to obtain a vibrato effect when a quartz oscillator is used. Usually, therefore, an LC oscillator including a variable capacitor is provided separately and in parallel therewith for being selectively used. This LC oscillator is, however, poor in stability and is not suitable as a main oscillator.

Furthermore, it is also known to provide LC oscillators for twelve scale signals. These are simultaneously used for vibrato effect. However, this arrangement is defective being poor in stability and difficult in adjustment of the oscillation frequency.

SUMMARY OF THE INVENTION This invention has as an object the provision of a vibrato effect which can be obtained by using a main oscillator of high accuracy such as a quartz oscillator or the like.

The invention is characterized in that an AND gate circuit is interposed in a circuit connected between a high frequency oscillator and an octave frequency divider, and in that an astable multivibrator modulated by a vibrator oscillator is provided. The multivibrator is so arranged that the AND gate circuit is controlled by the output signal thereof.

BRIEF DESCRIPTION OF THE DRAWING DETAILED DESCRIPTION Embodiments of this invention will be explained hereinafter with reference to the accompanying drawings, but prior thereto a frequency dividing system of an octave frequency divider will be first explained.

As for a frequency dividing system in the form of an octave frequency divider, there are two systems at present. A first system is such that, as shown in FIG. 1, twelve counter circuits respectively having frequency dividing ratios l/239, l/253 1/45l, are connected in parallel one with another to a high frequency oscillator 1'. If it is assumed that an oscillation frequency of 8369.21 Hz is to be obtained at the output terminal of the first counter circuit, an oscillation frequency fm of the high frequency oscillator 1' becomes 239 times that frequency, that is, 2.00024 MHz. Oscillation frequencies respectively obtained at the remaining output terminals of these counter circuits are shown in the same figure.

A second system is such that, as shown in FIG. 2, twelve counter circuits, each being 185/196 in frequency dividing ratio, are connected in series with one another and with a high frequency oscillator 1". If it is assumed that the oscillation frequency of 8372.02 Hz is to be obtained at the output terminal of the first counter circuit, the oscillation frequency of the high frequency oscillator 1" must be 196/185 times that frequency or, in other words, 8869.84 Hz. Oscillation frequencies respectively obtained at output terminals of these counter circuits are shown in FIG. 2.

These octave frequency dividers 2' and 2" are each frequency-divided into seven stages by using a plurality of I/Z-frequency dividers if it is intended to cover, for example, the whole seven octaves of a piano.

Next, one embodiment of this invention wherein the first frequency dividing system octave frequency divider 2' is used will be explained.

The oscillation frequency of a high frequency oscillator l is selected to be higher than the oscillation frequency required by the frequency divider 2. For example, the frequency is chosen to be 4.00048 MHz which is 2 times 2.00024 MHz. An AND gate circuit 3 is interposed in a circuit connected between the main oscillator l and the octave frequency divider 2'. Separately therefrom, there is provided an astable multivibrator 5 modulated by an oscillation frequency (for example, 5 10 Hz) ofa vibrato oscillator 4. The AND gate circuit 3 is controlled so as to be opened and closed by an output signal of the multivibrator 5.

FIG. 4 shows a specific example of a vibrato oscillator 4 and astable multivibrator 5. The vibrato oscillator 4 comprises an astable multivibrator and including transistors T1 and T2. The output waveform thereof (FIG. 5(a)) is applied to the base bias terminal 7 of the astable multivibrator 5 through a waveform forming circuit 6 comprising resistors RI and R2 and capacitors Cl and C2 (FIG. 5(b)). The oscillation frequency of the astable multivibrator 5 is higher than several KHz but is lower than the oscillation frequency of the main oscillator 1, and the output waveform obtained at output terminal A thereof changes as shown in FIG. 5(C) as the voltage changes at the base bias terminal 7. The

output waveform obtained at an output terminal B is reversed in waveform to that obtained at the output terminal A and is not otherwise different therefrom. The vibrato oscillator 4 may be a phase-shifting type oscillator or the like.

The AND gate circuit 3 is opened by the output waveform shown inFlG. 5(0). Thus, there is obtained at the output of gates a vibrato signal as shown in FIG. 5(e). As is seen nearly l/2 of the oscillation frequency fm FIG. 5(d) of the high frequency oscillator I is blocked according to the change of the pulse width.

If it is assumed that the output of the astable multivibrator 5 is a symmetrical waveform of 20 KHz, the quiescent time I, and the pulse width 1 have the relationship I, t 25 p. S. The oscillation frequency of the high frequency oscillator l is fm 4.00048 MHz and the pulse width thereof is 0.25 p. S.

The output frequency of the AND gate circuit 3 when such a symmetrical waveform is used can be obtained by the following formula:

t l/fm 1/r r frn X alt, Accordingly,

4.00048 X 25/25 25 2.00024 MHZ If it is asymmetrical and t, 25 p. S and t 24 p. S, 4.00048 X 24/25 24 1.9594 MHZ If it is asymmetrical and t 25 S and t 26 p. S,

4.00048 X'26/25 26 2.03946 MHZ I output terminal A.

In the example shown in FIG. 3, counter circuit 8 having a frequency dividing ratio of H2 is provided on the output side of the high frequency oscillator l and.

is so arranged that it and the output terminal of the AND gate circuit 3 are selectively connected to the octave frequency divider 2 througha change-over switch 9. Thereby, selection between the case where the vibrato effect is applied and the case where the vibrato effect is not applied can be made.

Another embodiment is shown in FIG. 6. It is such that the foregoingcounter circuit 8 required when the vibrato effect is not applied is omitted. The high frequency oscillator 1 is sufficient with 2.00024 l-IMz. In this embodiment, there are provided a waveform forming circuit 10a directly connected to the output side of the high frequency oscillator l and a waveform forming circuit 10b connected to the same oscillator 1' through a NOT circuit 11. The output terminals of these circuits 10a and 10b are connected to the AND gate circuit 3 through an OR circuit 12. This is the same as the foregoing embodiment except that a two fold oscillation frequency 4.00048 MHz is obtained by adding the output pulses of waveform forming circuits 10a and 10b at the output terminal of the OR circuit 12. 1

The above pertains to the case where the first frequency dividing system octave frequency divider is used. There is, however, no difference even in the case where the second frequency dividing system is used, except that the oscillation frequency of the high'frequency oscillator 1 is lower.

Thus, according to this invention, the AND gate circuit is interposed in the circuit connected between the high frequency oscillator and the octave frequency divider. Thereis further provided an astable multivibrawith high accuracy canbe used as the high frequency oscillator. Thereby the oscillation frequency can bestable.

What is claimed is:

l. A musical instrument comprising oscillator means, octave frequency divider means, gating means coupling said oscillator and divider means, multivibrator means coupled to and controlling said gating means, and vibrato oscillator means coupled to and controlling said multivibrator means, said instrument further comprising switching means selectively coupling said gating means to said divider means.

2. A musical instrument as claimed in'claim 1 comprising counter means interchangeably coupling said oscillator means with said divider means under the control of said switching means.

3. A musical instrument as claimed in claim 1 comprising parallel waveforming means, NOT gating means coupling one of said waveforming means to said oscillator means, the other of said waveforming means being coupleddirectly to said oscillator means,and OR gating means coupling said waveforming means to the first said gating means.

4. A musical instrument as claimed in claim 1 wherein said octave frequency dividing means includes a plurality of frequency dividing means connected in series.

5. A musical instrument as claimed in claim 1 wherein the vibrato oscillator means modulates the multivibrator means at a frequency of about 5-10 Hz.

said oscillator and divider means, multivibrator means coupled to and controlling said gating means, and vibrato oscillator means coupled to and controlling said multivibrator means, said octave frequency dividing means including a plurality of frequency dividing means connected in parallel and having different frequency dividing characteristics. 

1. A musical instrument comprising oscillator means, octave frequency divider means, gating means coupling said oscillator and divider means, multivibrator means coupled to and controlling said gating means, and vibrato oscillator means coupled to and controlling said multivibrator means, said instrument further comprising switching means selectively coupling said gating means to said divider means.
 2. A musical instrument as claimed in claim 1 comprising counter means interchangeably coupling said oscillator means with said divider means under the control of said switching means.
 3. A musical instrument as claimed in claim 1 comprising parallel waveforming means, NOT gating means coupling one of said waveforming means to said oscillator means, the other of said waveforming means being coupled directly to said oscillator means, and OR gating means coupling said waveforming means to the first said gating means.
 4. A musical instrument as claimed in claim 1 wherein said octave frequency dividing means includes a plurality of frequency dividing means connected in series.
 5. A musical instrument as claimed In claim 1 wherein the vibrato oscillator means modulates the multivibrator means at a frequency of about 5-10 Hz.
 6. A musical instrument as claimed in claim 1 wherein said multivibrator means includes an astable multivibrator.
 7. A musical instrument as claimed in claim 1 wherein said vibrato oscillator means is a phase shifting type of oscillator.
 8. A musical instrument as claimed in claim 1 wherein the first said oscillator means includes a quartz oscillator.
 9. A musical instrument comprising oscillator means, octave frequency divider means, gating means coupling said oscillator and divider means, multivibrator means coupled to and controlling said gating means, and vibrato oscillator means coupled to and controlling said multivibrator means, said octave frequency dividing means including a plurality of frequency dividing means connected in parallel and having different frequency dividing characteristics. 